The long-term objective of this proposal is to understand the molecular mechanisms which regulate the growth and differentiation of human epidermis. The health-relatedness of this objective lies in the use of the information acquired to design rational therapy for skin disease and to increase our understanding of skin disease pathogenesis. The main purpose of the proposed studies is to test crucial elements of two related hypotheses: A) that transforming growth factor-alpha (TGF-a) regulates the expression of keratinocyte protooncogenes, cytokines, and other mediators of proliferation and inflammation via signal transduction pathways known to be abnormal in psoriasis, and B) that TGF-alpha regulates a hyperproliferative mode of keratinocyte differentiation observed in cultured keratinocytes, wound healing, psoriasis and other epidermal hyperproliferative states. The Specific Aims of this proposal are: 1) to define the role of the EGF receptor tyrosine kinase activity in the autoregulation of TGF-alpha, 2) to evaluate the effects of the KC antiproliferative agents transforming growth factor-Beta (TGF-Beta) and cyclosporin A (CsA) on TGF-alpha- induced KC phospholipid metabolism and gene expression, 3) to analyze the transcription and chromatin structure of the TGF-alpha gene, 4) To analyze the effects of transfected v-erb-B tyrosine kinase activity and antisense oligonucleotides to TGF-alpha on TGF-alpha gene expression and KC proliferation and 5) to analyze TGF-alpha gene expression in early lesions of psoriasis. These studies will be conducted in the Dermatology Research Unit of the University of Michigan on samples of normal and psoriatic human epidermis obtained by punch or keratome biopsy, on keratinocyte cultures obtained from these biopsies. The methods to be used include: RNA analysis by blot hybridization, nuclear runoff transcription, and in situ hybridization; lipid analysis by radiolabelling, organic solvent extraction, and immunofluorescence; chromatin structure analysis by nuclease digestion and blot hybridization, and gene transfer into keratinocytes.